Benzaldehydes and benzoic acids having trifluoromethyl or trifluoromethoxy substituents, with or without additional fluorine substituents, are described extensively in the chemical literature as starting materials for the synthesis of active ingredients (for example U.S. Pat. No. 3,830,805 for aldehydes, EP-A-612 723 for benzoic acids), electronics materials, (JP-A-06 025 120) or generally as intermediates (EP-B-0 396 987).
However, there is a need for trifluoromethyl- and trifluoromethoxybenzaldehydes and benzoic acids having additional functionalities, since these functionalities ease or even make possible introduction into the target structures. The aim of modifying the activity of agrochemicals or pharmaceuticals through fluorination in the form of the trifluoromethyl or trifluoromethoxy group, with or without additional fluorine substituents on the aromatic ring is achieved by varying the lipophilicity and/or the dipolar moment (Kanie et al., Bull. Chem. Soc. Jpn. 2000, 73, 471). It may also be desirable for electronics materials, in particular liquid crystals, to vary the dipolar moment.
The invention accordingly provides compounds of the formula (I) 
where substituents X1, X2, Y and Z are defined as follows:
X1 is H or F
X2 is H or F
Y is CI, Br or I
Z is CHO or COOH or CN
n is 0 or 1
Preference is given to the following compounds in which
a1) X1 and X2: H
Y: Cl or Br
Z: CHO
a2) X1 and X2: H
Y: Cl or Br
Z: COOH
a3) X1 and X2: H
Y: Cl or Br
Z: CN
b1) X1: F X2: H
Y: Cl or Br
Z: CHO
b2) X1: F X2: H
Y: Cl or Br
Z: COOH
b3) X1: F X2: H
Y: Cl or Br
Z: CN
c1) X1 and X2: F
Y: Cl or Br
Z: CHO
c2) X1 and X2: F
Y: Cl or Br
Z: COOH
c3) X1 and X2: F
Y: Cl or Br
Z: CN;
in particular
2-chloro-6-fluoro-5-trifluoromethylbenzaldehyde
2-bromo-6-fluoro-5-trifluoromethylbenzaldehyde
2-chloro-6-fluoro-5-trifluoromethoxybenzaldehyde
2-bromo-6-fluoro-5-trifluoromethoxybenzaldehyde
2-chloro-4,6-difluoro-5-trifluoromethylbenzaldehyde
2-bromo-4,6-difluoro-5-trifluoromethylbenzaldehyde
2-chloro-4,6-difluoro-5-trifluoromethoxybenzaldehyde
2-bromo-4,6-difluoro-5-trifluoromethoxybenzaldehyde
2-chloro-6-fluoro-5-trifluoromethylbenzoic acid
2-bromo-6-fluoro-5-trifluoromethylbenzoic acid
2-chloro-6-fluoro-5-trifluoromethoxybenzoic acid
2-bromo-6-fluoro-5-trifluoromethoxybenzoic acid
2-chloro-4,6-difluoro-5-trifluoromethylbenzoic acid
2-bromo-4,6-difluoro-5-trifluoromethylbenzoic acid
2-chloro-4,6-difluoro-5-trifluoromethoxybenzoic acid
2-bromo-4,6-difluoro-5-trifluoromethoxybenzoic acid
The invention further provides a process for preparing the compounds of the formula (I) where Z=CHO, wherein, a halobenzene of the formula (II) (wherein n, Y, X1 and X2 are each as defined in formula (1) in a solvent or solvent mixture at a temperature which does not support aryne formation is reacted with an organolithium compound. The molar ratio of lithium compound to starting product (II) is preferably 1:1 to 1.2:1. The lithium compound obtained, again at a temperature which does not support aryne formation, is reacted with one formyl equivalent of the formula (III) and then subjected to a hydrolysis to (I). The molar ratio (II):(II) is preferably from 1:1 to 1:2. 
In (III), R1 is an alkyl radical having from 1 to 6 carbon atoms, a trimethylsilyl radical or an (optionally substituted) phenyl radical, R2 is an alkyl radical having from 1 to 6 carbon atoms, a trimethylsilyl radical or an (optionally substituted) phenyl radical and R3 is xe2x80x94CH(xe2x95x90O) or xe2x80x94CH(OR4)2; R1 and R2 together with the nitrogen atom may also be part of a five- to seven-membered ring. R4 is an alkyl radical having from 1 to 4 carbon atoms.
Preference is given to reacting (II) with organolithium compounds at a temperature below xe2x88x9260xc2x0 C., very particular preferably below xe2x88x9270xc2x0 C., in particular at a temperature in the range from xe2x88x9270xc2x0 C. to xe2x88x92110xc2x0 C. The reaction times are in general from 1 to 8 hours. On completion of the reaction (detectable, for example, by TLC or GC), the reaction mixture is gradually heated to xe2x88x9225 to xe2x88x9215xc2x0 C. and cautiously hydrolyzed using water. The mixture is then acidified using hydrochloric acid to a pH of from 1 to 5 and extracted with a suitable solvent (for example tert-butyl methyl ether, dichloromethane, ethyl acetate, toluene). The extracts of the organic phase are combined and dried, for example, over sodium sulfate). The solvent may be removed under reduced pressure to obtain the desired compound of the formula (I). Any purification required may be effected by chromatography, distillation or crystallization or a combination of the methods mentioned.
The yields are customarily in the range from 50 to 90%, based on (II).
The organolithium compound is preferably the lithium compound of a secondary amine, preferably having sterically demanding substituents. Particular preference is given to lithiumdiisopropylamide, lithium-2,2,6,6-tetramethylpiperidide, lithium dicyclohexylamide, lithium cyclohexylisopropylamide and lithium bis(trimethylsilyl)amide. Very particular preference is given to lithium 2,2,6,6-tetramethylpiperidide and lithium diisopropylamide.
For the compounds of the formula (II) where Y is CI, the organolithium compound is an alkyllithium compound or the lithium compound of a secondary amine; preference is given to n-butyllithium.
Potassium tert-butoxide may also optionally be added for better activation.
In a preferred embodiment, Y in formula (II) is Br.
It may also be advantageous to add materials to the reaction mixture which activate it or influence the selectivity, for example tetramethylethylenediamine or potassium tert-butoxide (preference is given to the latter in the case of compounds of the formula (II) where Y is CI).
The formyl equivalent of the formula (III) is preferably N,N-dimethylformamide, N,N-diethylformamide, N,N-dipropylformamide, N,N-diisopropylformamide, N,N-dibutylformamide, N-formylpyrrolidine, N-formylmorpholine, N-formylpiperidine, dimethylformamide dialkyl acetal, N-methylformanilide, N-ethylformanilide or N,N-bis(trimethylsilyl)formamide. The formyl equivalent of the formula (III) is most preferably N,N-dimethylformamide.
For the purposes of the present invention, useful solvents are aprotic solvents, for example ether such as tetrahydrofuran, 1,2-dimethoxyethane, 1,4-dioxane, diethyl ether, or hydrocarbons such as hexane, cyclohexane, heptane, pentane or mixtures of aprotic solvents.
The reaction of (II) with the organolithium compound may also be effected in the presence of the compound (III), so that the lithium derivative of (II) formed in situ can react directly with (III). For this purpose, it may be necessary and advantageous to carry out the reaction above xe2x88x9260xc2x0 C., for example in the range from xe2x88x9220 to +25xc2x0 C.
The invention further provides a process for preparing compounds of the formula (I) where Z=COOH, wherein a halobenzene of the formula (II) (where E, Y, X1 and X2 are each as defined above) in a solvent or solvent mixture at a temperature which does not support aryne formation is reacted with an organolithium compound. The molar ratio of lithium compound: starting product (II) is preferably from 1:1 to 1.2:1. The lithium compound obtained, again at a temperature which does not support aryne formation, is reacted with carbon dioxide (CO2) and then subjected to hydrolysis (I). 
Preference is given to reacting (II) with the organolithium compound at a temperature below xe2x88x9260xc2x0 C., very particular preference below xe2x88x9270xc2x0 C., in particular at a temperature in the range from xe2x88x9270xc2x0 C. to xe2x88x92110xc2x0 C. The reaction times are in general from 1 to 8 hours. On completion of the reaction (detectable, for example, by TLC or GC), the reaction mixture is gradually heated to xe2x88x9225 to xe2x88x9215xc2x0 C. and cautiously hydrolyzed using water. The mixture is then acidified using hydrochloric acid to a pH of from 1 to 5 and extracted with a suitable solvent (for example tert-butyl methyl ether, dichloromethane, ethyl acetate, toluene). The extracts of the organic phase are combined and dried, for example, over sodium sulfate. The solvent may be removed under reduced pressure to obtain the desired compound of the formula (I). Any purification required may be effected by chromatography, distillation or crystallization, precipitation or a combination of the methods mentioned.
The yields are customarily in the range from 50 to 90%, based on (II).
The organolithium compound is preferably the lithium compound of a secondary amine, preferably having sterically demanding substituents. Particular preference is given to lithiumdiisopropylamide, lithium-2,2,6,6-tetramethylpiperidide, lithium dicyclohexylamide, lithium cyclohexylisopropylamide and lithium bis(trimethylsilyl)amide. Very particular preference is given to lithium 2,2,6,6-tetramethylpiperidide and lithium diisopropylamide.
For the compounds of the formula (II) where Y is CI, the organolithium compound is an alkyllithium compound or the lithium compound of a secondary amine; preference is given to n-butyllithium.
Potassium tert-butoxide may also optionally be used for better activation.
In a preferred embodiment, Y in formula (II) is Br.
It may also be advantageous to add materials to the reaction mixture which activate it or influence the selectivity, for example tetramethylethylenediamine or potassium tert-butoxide (preference is given to the latter in the case of compounds of the formula (II) where Y is CI).
The carbon dioxide may be added to the reaction mixture on completed metallation in the form of dry ice or the reaction mixture may added to an excess of dry ice. However, it is also possible to pass gaseous carbon dioxide into the reaction mixture, preferably at temperatures above xe2x88x9275xc2x0 C.
For the purposes of the present invention, useful solvents are aprotic solvents, for example ethers such as tetrahydrofuran, 1,2-dimethoxyethane, 1,4-dioxane, diethyl ether, or hydrocarbons such as hexane, cyclohexane, heptane, pentane or mixtures of aprotic solvents.
The invention further provides the use of compounds of the formula (I) as starting materials for preparing agrochemicals, electronics materialsxe2x80x94in particular for components of liquid crystalline mixturesxe2x80x94preferably for fluorinated derivatives of fluorene or phenanthrenexe2x80x94and pharmaceuticals (in particular angiotensin II antagonists).
For this purpose, the compounds of the formula (I) are particularly suitable, since both the aldehyde function (for example by Wittig reaction, reduction to the benzyl alcohol, condensation with Cxe2x80x94Hxe2x80x94, Nxe2x80x94Hxe2x80x94 or Sxe2x80x94H compounds) and the halogen function (which refers here to the function of the substituent Y) (for example by Suzuki coupling, Grignard reaction, Heck reaction) are available for reactions and alsoxe2x80x94under special conditions in the case of compounds or the subsequent products derived from them in which X1 is F, very particularly in the case of compounds or the subsequent products derived from them in which X1 and X2 are both Fxe2x80x94the reactivity of a difluoroaromatic (for example by ortho-metallation) or of a trifluoroaromatic (for example by aromatic nucleophilic substitution) may be utilized.